Data API Documentation

Here we document how to request data from our data API and specify the format of the returned data. This document is an in-depth reference. For an easy interface to build your request URL, see the URL Builder tool.

Our data API is brand new and in beta testing. If there is some aspect where we could do better or a feature to consider, please let us know: Email Zach.Schwalbe@colostate.edu.

Bugfixes Apr 9, 2021

• NaNs (not-a-number) are now detected in the data and replaced with -999.

Bugfixes Feb 9, 2021

• Some timestamps were negative or greater than 23:59:59, causing parse errors. These odd cases are now handled (though they're probably bad data).
• Some station IDs in the observation data are returned from the database in uppercase, causing a lookup failure. These are now normalized to lowercase.

Changes and Bugfixes Jan 13, 2021

Another round of fixed bugs and formatting changes:

• Missing data - when whole observations are missing, they now show up in the data.
• For multi-station output in JSON format, each station's data is now in their own sub-objects. The time field is still at the top level since it is the same across all stations, and there is a stations field to make the list of included stations explicit. We hope this change makes it easier to work with the data rather than you having to write your own logic to split apart each stations' data. If you do want a combined collection of observations, the CSV format has that organization.
• The count field has been removed from JSON output. This value is already available in the arrays' .length value.
• New field "timestep" in JSON data and and metadata - for data, this is the number of seconds between observations for the requested frequency; for metadata it is the number of seconds between observations in the finest resolution the station has.

Changes and Bugfixes Dec 16, 2020

We have fixed same bugs and updated behavior:

• The station field was missing from some output. This has been restored.
• Missing dates in CSV were not showing up as empty quotes (""). This has been fixed.
• Missing dates in JSON now show up as an empty string ("") for uniformity with CSV
• Missing numeric values are no longer marked as null in JSON output; -999 is used to help Javascript interpreters keep things monomorphic
• When whole observations are missing, they now appear in the output. The missing fields have their missing value: -999 for numbers and "" for dates.
• In station metadata, "active" now has the boolean value true or false in JSON format.

URL Structure and Query Parameters

Data request URLs for all stations look like:

https://coagmet.colostate.edu/data/product.fmt?param=value…

or for just one station:

https://coagmet.colostate.edu/data/product/stnid.fmt?param=value…

Variable parts of the URL are:

• product - 5min/hourly/latest, daily/latest daily, gdd, soil moisture, or metadata.
• fmt - json or csv
• stnid - 5-character station id. See the list on the URL Builder page.
• param=value… - query parameters, documented below.

Query parameters are the part of the URL (web address) after the ? and are separated by &. They change various aspects of the data produced.

Station(s)

If you want data for all active stations, use the first URL form above. If you want data for one particular station, use the second form. If you want to select multiple particular stations (but not all), use the first form and add the

stns=id,id,…

query parameter, where id is a 5-character station id such as gby01 for our Granby station.

Inactive Stations

By default, "all stations" only includes stations currently in operation. If you also want inactive stations (without having to list their ids individually), use

inactive=yes

Date Ranges

The general way to specify dates is with the from= and to= parameters with ISO 8601 dates. These can take several forms:

• MM
• YYYY
• YYYY-MM
• YYYY-MM-DD
• YYYY-MM-DDTHH:MM

Where YYYY is the four-digit year, MM is the month (01-12), DD is the day of the month (01-31), HH is the hour of the day (00-23) and MM is the minute (00-59). The year by itself is the same as January 1 of that year.

If only the month is given, the from month will start on the first day of the month; the to month will end on the last day of the month. The year defaults to this year, but you can set the year with the year= query parameter. If only the year is given, the from date will be January 1 of that year whereas the to date will be December 31 of that year.

If you do not give a to date, the default is today. If you do not give a from date, the default is a number of days before the to date, with the number of days based on the data timestep. For daily data this is 7 days; for hourly data it is 5 days; and for 5-minute data it is 3 days. You can override the default number of days with the span= query parameter. If you give only one of from= or to=, the other date will be set based on this span.

Timezone.  For a 5 minute or hourly data set, if you specify a timezone with the tz= query parameter (see below), the from and to dates/times will be converted from that timezone into MST before querying the database (we store our records in MST). When requesting daily data, the dates are always interpreted as MST.

Units

We default to US units, so add the parameter

units=m

to select metric units.

Timezone

We store times in Mountain Standard Time (MST) and that is the default timezone (UTC-7). To select the UTC/GMT timezone, use

tz=utc

If you add

tz=co

to the request, the data will be in MST or MDT (UTC-6) based on the date range of the data. Where the dates cross the daylight saving time change, the code picks MST or MDT based on which one more of the data is in. Accuracy is not guaranteed.

If you use the query parameters from= or to= and the data timestep is hourly or 5 minute, the date/time range will be interpreted in the given timezone. Daily data will use exactly the date given in MST.

Headers

this applies to CSV only. To output column headers use

headers=yes

otherwise headers will not be added to the output.

GDD Parameters

the GDD calculation requires a base and max temperature within which the plant is able to grow. The defaults of 50-86°F (10-30°C) are usually good, but your crop may be different. You can set the base and max temperature with the

base=temp

and/or

max=temp

query parameters where temp is a temperature in Fahrenheit unless units=m was also requested, in which case the temperatures are in °C.

Fields

Most data fields are included in the default output, documented in detail below. If you want more or fewer fields, use the

flds=

query parameter. List the fields you want, separated by commas, e.g. flds=t,rh,windSpeed.

Optional Metadata

By default, station metadata does not include the instruments or owner/sponsors. To include this data, add the query parameters

instruments=yes

and/or

sponsors=yes

Data Formatting

Numbers

Numbers are some number of digits with or without a decimal point ('.'), e.g. 123.45. We do not use scientific notation, i.e. 'e' followed by an exponent. There are no commas in numbers. Missing values are given the dummy value -999.

Date and Time Formats

the default date format for CSV data is the US convention MM/DD/YYYY. For JSON we use ISO 8601 YYYY-MM-DD or YYYY-MM-DDTHH:MM. To override the default, use either

dateFmt=us

or

dateFmt=iso

Times are in the format HH:MM. Missing dates are written as an empty string, i.e. "".

Relative Humidity

This is a number formatted as a fractional value. That is, 35% relative humidity will be formatted as 0.35.

Wind and Gust Directions

This is in degrees clockwise from due north. For example, an East-northeast window (blowing to West-southwest) is 67.5. A Northwest wind would be 315.

JSON

Our JSON-formatted data is encapsulated in one outer 'object'. Except for metadata, all JSON output has the following fields:

• "which":  "raw" or "qc" (default),
• "frequency":  "5min", "hourly", "daily" or "latest",
• "timestep"  300, 600, 900, 3600, 86400 (5 minute, 10 minute, 15 minute, hourly and daily in seconds),
• "timezone":  "mst" (default), "co" or "utc",
• "tzOffset":  "-07:00" (MST), "-06:00" (MDT) or "+00:00" (UTC),
• "units":  "us" (default) or "m",

The data fields are all arrays of their particular data type. They are parallel arrays, so that the values of one observation are stored at the same index of each array.

Numbers are as described above.

Because JSON does not have a standard date or time format, we put the values in strings. Dates are in ISO (default) or US format as described in Date and Time Formats above. Missing date/times will show up as an empty string, i.e. "".

Examples

Single Station. Request URL: https://coagmet.colostate.edu/data/hourly/gby01.json?flds=t,rh,dewpt,solarRad,precip&from=2021-01-10T10:00&to=2021-01-10T13:00

{
  "which": "qc",
  "frequency": "hourly",
  "timestep": 3600,
  "timezone": "mst",
  "tzOffset": "-07:00",
  "units": "us",
  "station": "gby01",
  "time": ["2021-01-10T10:00","2021-01-10T11:00","2021-01-10T12:00","2021-01-10T13:00"],
  "t": [-3.9,4.6,14.5,17.8],
  "rh": [0.825,0.74,0.496,0.469],
  "dewpt": [-7.9,-1.9,-1.0,0.9],
  "solarRad": [254.0,389.0,459.7,472.3],
  "precip": [0.0,0.0,0.0,0.0]
}

Multiple Stations. Request URL: https://coagmet.colostate.edu/data/hourly.json?flds=t,rh,dewpt,solarRad,precip&stns=ctr01,drg01&from=2021-01-10T10:00&to=2021-01-10T13:00

{
  "which": "qc",
  "frequency": "hourly",
  "timestep": 3600,
  "timezone": "mst",
  "tzOffset": "-07:00",
  "units": "us",
  "stations": ["ctr01","drg01","egl01","gby01"],
  "time": ["2021-01-10T10:00","2021-01-10T11:00","2021-01-10T12:00","2021-01-10T13:00"],
  "ctr01": {
    "t": [14.1,18.4,21.7,-999.0],
    "rh": [0.798,0.723,0.716,-999.0],
    "dewpt": [9.0,11.0,14.0,-999.0],
    "solarRad": [319.5,435.5,504.5,-999.0],
    "precip": [0.0,0.0,0.01,-999.0]
  },
  "drg01": {
    "t": [25.6,31.6,35.3,35.4],
    "rh": [0.817,0.635,0.55,0.541],
    "dewpt": [20.7,20.6,20.7,20.4],
    "solarRad": [186.3,384.2,344.5,260.0],
    "precip": [0.0,0.0,0.0,0.0]
  }
}

CSV

Numbers are as described above.

Dates are always quoted whether US format MM/DD/YYYY (default) or ISO 8601 YYYY-MM-DD. Times are formatted MM/DD/YYYY HH:MM for US or YYYY-MM-DDTHH:MM for ISO. If you requested tz=utc, a " Z" will be appended to the time to indicate that. Missing dates will show up as empty quotes, i.e. "".

Example

Request URL: https://coagmet.colostate.edu/data/hourly.csv?headers=yes&flds=t,rh,dewpt,solarRad,precip&stns=ctr01,drg01&from=2021-01-10T10:00&to=2021-01-10T13:00

Station,"Date and Time","Air temp",RH,Dewpoint,"Solar rad",Precip
id,"date time","deg F","%","deg F",W/m2,in
ctr01,"01/10/2021 10:00",14.1,0.798,9.0,319.5,0.0
ctr01,"01/10/2021 11:00",18.4,0.723,11.0,435.5,0.0
ctr01,"01/10/2021 12:00",21.7,0.716,14.0,504.5,0.01
ctr01,"01/10/2021 13:00",-999.0,-999.0,-999.0,-999.0,-999.0
drg01,"01/10/2021 10:00",25.6,0.817,20.7,186.3,0.0
drg01,"01/10/2021 11:00",31.6,0.635,20.6,384.2,0.0
drg01,"01/10/2021 12:00",35.3,0.55,20.7,344.5,0.0
drg01,"01/10/2021 13:00",35.4,0.541,20.4,260.0,0.0

Note the optional header lines and -999.0 missing value.

Latest Data

URLs for the latest data for all or just one station, respectively:

https://coagmet.colostate.edu/data/latest.fmt?param=value…
https://coagmet.colostate.edu/data/latest/stnid.fmt?param=value…

The latest data has the same fields as 5 minute and hourly data. It consists of the newest observations for each station, usually a 5 minute observation, but some stations only have hourly data available.

Note that if you request JSON-formatted data for one station, the data will not be in arrays.

Latest Daily Data

URLs for the latest daily data for all or just one station, respectively:

https://coagmet.colostate.edu/data/latest/daily.fmt?param=value…
https://coagmet.colostate.edu/data/latest/daily/stnid.fmt?param=value…

The latest daily data has the same fields as daily data. For JSON-formatted data for one station, the fields will not be in arrays.

5 Minute and Hourly Data

5 minute URLs for all or just one station, respectively:

https://coagmet.colostate.edu/data/5min.fmt?param=value…
https://coagmet.colostate.edu/data/5min/stnid.fmt?param=value…

Hourly URLs for all or just one station:

https://coagmet.colostate.edu/data/hourly.fmt?param=value…
https://coagmet.colostate.edu/data/hourly/stnid.fmt?param=value…

Despite the difference in timestep, 5-minute and hourly data have the same fields, they are just averaged over a different time span.

Field	Description	US	Metric
station	station id	stn01	stn01
time	observation date and time	MM/DD/YYYY	YYYY-MM-DDTHH:MM:SS
t	air temperature	°F	°C
rh	relative humidity	0.35	0.35
dewpt	dew point	°F	°C
vp*	vapor pressure	kPa	kPa
solarRad	solar radiation	W/m2	W/m2
rso*	clear-sky solar radiation	W/m2	W/m2
windSpeed	wind speed	mph	m/s
windDir	wind direction	°N	°N
windStdDev*	wind direction std. dev.	mph	m/s
precip	precipitation	in	mm
st5cm	soil temperature 5cm down	°F	°C
st15cm	soil temperature 15cm down	°F	°C
gustSpeed	gust speed	mph	m/s
gustTime*	gust time	HH:MM	HH:MM
gustDir	gust direction	°N	°N

* fields not present in default request

Daily Data

URLs for daily data for all or just one station, respectively:

https://coagmet.colostate.edu/data/daily.fmt?param=value…
https://coagmet.colostate.edu/data/daily/stnid.fmt?param=value…

Field	Description	US	Metric
station	station id	stn01	stn01
date	observation date	MM/DD/YYYY	YYYY-MM-DDTHH:MM:SS
tAvg	average air temp	°F	°C
tMax	max air temp	°F	°C
tMaxTime	time of max air temp	HH:MM	HH:MM
tMin	min air temp	°F	°C
tMinTime	time of min air temp	HH:MM	HH:MM
rhMax	max relative humidity	0.35	0.35
rhMaxTime	time of max rh	HH:MM	HH:MM
rhMin	min relative humidity	0.35	0.35
rhMinTime	time of min rh	HH:MM	HH:MM
vp*	vapor pressure	kPa	kPa
solarRad	solar radiation (insolation)	W/m2	W/m2
rso*	clear-sky solar radiation	W/m2	W/m2
precip	precipitation	in	mm
windRun	total distance wind traveled	mi	km
gustSpeed	max wind gust	mph	m/s
gustTime	time of max wind gust	HH:MM	HH:MM
gustDir	gust direction	°N	°N
etrASCE	ASCE ref. evapotranspiration (ET)	in	mm
etrPK	Penman-Kimberly ref. ET	in	mm
etrHourly	hourly ASCE ET	in	mm
etoASCE	ASCE small thing ET	in	mm
st5Max	5cm soil temperature	°F	°C
st5MaxTime	time of max 5cm soil temp	HH:MM	HH:MM
st5Min	5cm min soil temp	°F	°C
st5MinTime	time of min 5cm soil temp	HH:MM	HH:MM
st15Max	15cm soil temperature	°F	°C
st15MaxTime	time of max 15cm soil temp	HH:MM	HH:MM
st15Min	15cm min soil temp	°F	°C
st15MinTime	time of min 15cm soil temp	HH:MM	HH:MM

* fields not present in default request

Growing Degree Days (GDD) Data

URLs for GDD data for just one station:

https://coagmet.colostate.edu/data/gdd/stnid.fmt?param=value…

Growing degree days is a somewhat involved calculation, so we only support single station requests. If your crop grows over an unusual temperature range (outside 50-86°F), you can set the temperature parameters.

Field	Description	US	Metric
station	station id	stn01	stn01
time	observation date and time	MM/DD/YYYY	YYYY-MM-DDTHH:MM:SS
gdd	cumulative GDD since planting date	°F	°C
daily	daily fraction of GDD	°F	°C
hist	historical avg GDD	°F	°C

No fields are missing from the default output.

Soil Moisture Data

URLs for hourly soil moisture data for all or just one station, respectively:

https://coagmet.colostate.edu/data/hourly/soilmoisture.fmt?param=value…
https://coagmet.colostate.edu/data/hourly/soilmoisture/stnid.fmt?param=value…

URLs for daily soil moisture data for all or just one station:

https://coagmet.colostate.edu/data/daily/soilmoisture.fmt?param=value…
https://coagmet.colostate.edu/data/daily/soilmoisture/stnid.fmt?param=value…

Hourly and daily soil moisture have all the same fields, just averaged over different time spans. This is somewhat specialized data, so we have only made it available in metric units whether you include the units=m query parameter or not.

Field	Description	Units
station	station id	stn01
time	observation date and time	YYYY-MM-DDTHH:MM:SS
vwc4	4" volumetric water content	m3/m3
ec4	4" electrical conductivity	m3/m3
st4	4" soil temperature	°C
vwc24	24" volumetric water content	m3/m3
ec24	24" electrical conductivity	m3/m3
st24	24" soil temperature	°C

No fields are missing from the default output.

Station Metadata

URLs for metadata for all or just one station:

https://coagmet.colostate.edu/data/metadata.fmt?param=value…
https://coagmet.colostate.edu/data/metadata/stnid.fmt?param=value…

Metadata has a slightly different structure from our normal data products. Each station id is a key in the outermost object that wraps all data. The station's metadata is in its own object under that station id key.

Query parameters that apply to station metadata:

• instruments=yes - includes the instrument fields (see below).
• sponsors=yes - includes the owner and sponsors fields (also see below).
• units=m - station elevation and anemometer height will be in meters.

The metadata fields cannot be individually selected. Instead, the default fields are listed in the first table. The other tables are the fields included when instruments or sponsors parameters are enabled.

Field	Description	US	Metric
station	station id	stn01	stn01
name	station name
location	text description of the station's location
lat		°N	°N
lon		°E	°E
elevation	station elevation above sea level	ft	m
anemometerHeight	height of wind sensor above ground level	ft	m
active	is the station in operation?	JSON: true/false, CSV: active/inactive
irrigation	type of irrigation near the station	full/part/dry/unknown
firstObs	first date of data available	MM/DD/YYYY	YYYY-MM-DD
lastObs	last date of data available	MM/DD/YYYY	YYYY-MM-DD
timestep	The time between observations	seconds	seconds

Instruments

Field	Description
logger	the data logger that records and transmits observations
tempRH	the temp/rh instrument
anemometer	wind speed and direction sensor
soilThermometer	soil thermometer
rainGauge	rain gauge

Owner and Sponsors

Field	Description
owner	who owns the station*
sponsors	a list of sponsors for the station

* We operate the weather stations, without necessarily owning them. In JSON, this is an array of strings. In CSV, each sponsor is a separate quoted string. There can be up to 5 sponsors, so the header (if any) will be …,Owner,Sponsor1,Sponsor2,…,Sponsor5